[RISC-V] Fix GC regions virtual alloc after #80295

[t-mustafin]

Part of #84834

cc @janvorli @wscho77 @HJLeee @clamp03 @JongHeonChoi @gbalykov @viewizard @ashaurtaev @sirntar @yurai007 @tomeksowi @brucehoult @DenisParal

[ghost]

Tagging subscribers to this area: @dotnet/gc
See info in area-owners.md if you want to be subscribed.

Issue Details

---

Part of #84834

cc @janvorli @wscho77 @HJLeee @clamp03 @JongHeonChoi @gbalykov @viewizard @ashaurtaev @sirntar @yurai007 @tomeksowi @brucehoult @DenisParal

Author:	t-mustafin
Assignees:	-
Labels:	area-GC-coreclr, community-contribution
Milestone:	-

[gbalykov]

@janvorli please take a look, after #80295 changes from #84797 were disabled, which now leads to error during coreclr initialization on risc-v board on main branch

[janvorli]

@t-mustafin, @gbalykov I am sorry for breaking this for you. As for your fix, I'd prefer modifying the Unix version of GCToOSInterface::GetVirtualMemoryLimit() to return GCToOSInterface::GetVirtualMemoryMaxAddress() instead of (size_t)-1 if no rlimit is set and leaving the code in gc.cpp unchanged.

[janvorli]

LGTM, thank you!